This invention relates to a vibration-isolating apparatus adapted to support a vibration generating member, such as an engine of an automobile in a vibration isolating manner with respect to a body.
As the space saving techniques for the interior of an engine room of an automobile produced in recent years have been developed, functional parts have been miniaturized and arranged in a very narrowly spaced condition. Therefore, the conditions for repairing the functional parts have become increasingly severe, and the creation of functional parts of high durability and reliability has been demanded.
JP-Y1-1993-003789 (JP-Y1-05003789 or Japanese Utility Model Publication Examined No. 3789/1993) discloses a vibration-isolating apparatus (hereinafter referred as Prior Art 1) of the following structure, for supporting an engine in a vibration-isolating manner in such an engine room with respect to a vehicle body. This vibration-isolating apparatus comprises a first fixture secured to a bracket of an engine; a second fixture secured to a body; a vibration-isolating base body formed of an elastic material such as rubber interposed between and connecting together these two fixtures; a stopper rubber projecting outward from the portion of the vibration-isolating base body which is on the side of the second fixture; and a metal stopper fixed to the first fixture so as to surround the stopper rubber. The metal stopper and stopper rubber prevent an excess deformation of the vibration-isolating basebody. The metal stopper is formed of a metal plate by bending the same so as to have a substantially sideway-fallen J-shaped cross section so that the metal stopper has contact surfaces respectively parallel to stopper surfaces of the stopper rubber, stoppering action is achieved in all of the following three directionsxe2x80x94compression and drawing directions in which the first and second fixtures are moved relatively toward and away from each other; a radial direction perpendicular to these directions, for example, forward or backward direction of the vehicle; and a circumferential direction, for example, rightward or leftward direction of the vehicle. This metal stopper prevents damage on the elastic material constituting the vibration-isolating base body and stopper rubber.
On the other hand, JP-A-1997-079310 (JP-A-09079310, or Japanese Patent Publication Unexamined No. 79310/1997) discloses another vibration-isolating apparatus (hereinafter, referred as Prior Art 2) of the following structure. This apparatus includes a metal stopper which has the same shape as mentioned above and serves for restring displacements between upper and lower fixtures in all of following directionxe2x80x94compression and drawing directions in which the first and second fixtures are moved relatively toward and away from each other; a radial direction perpendicular to these directions, for example, forward or backward direction of the vehicle; and a circumferential direction, for example, rightward or leftward direction of the vehicle. The metal stopper is formed by bending a plate or sheet so as to have a substantially sideway-fallen J-shaped cross section and so as to be combined firmly with the first fixture. The metal stopper is bonded firmly to an upper part of a vibration-isolating base body formed of an elastic member such as rubber, in such a manner that the metal stopper is opposed to a stopper rubber.
In such vibration-isolating apparatuses, the durability and reliability thereof have increasingly been demanded. Especially, because an upward-facing contact surface of the metal stopper, which surface abuts on the stopper rubber when the metal stopper is displaced greatly in the drawing direction, has to come to the lower side of the stopper rubber by moving around the stopper rubber, it is desired that a slip-off of the metal stopper can be prevented even when a momentary large stress in drawing direction is applied.
However, the above-described vibration-isolating apparatus of Prior Art 2 is not satisfactory concerning its ability to prevent a slip-off of the metal stopper.
In view of the above, the present invention is aimed to provide a vibration-isolating apparatus and a metal stopper therefor which have a long-lasting durability and reliability.
As for Prior Art 1, in which a metal stopper is formed so as to surround a stopper rubber in three directions, the spatial dimensions for a stopper mechanism increases to cause a problem to occur in the mountability thereof.
The vibration-isolating apparatus supporting the engine is fixed in a rightwardly or leftwardly inclined state to a bracket in a vehicle. Therefore, whereas a large stress in rightward or leftward direction rarely cause an excessive stress to be exerted on other parts on the vehicle, a large stress in forward or backward direction causes the stopper rubber to collide with the metal stopper. By the collision, bending stress is exerted on fixing bolts for the second fixture on the lower side due to the reaction ascribed to the impact of the collision. This exerts an ill influence upon the sealability and fastening force between the lower side fixture and fixing bolts, and causes problems to occur in the reliability of the apparatus.
In the Prior Art 2, the metal stopper is merely formed by bending a plate or sheet so as to have a substantially sideway-fallen J-shaped cross section. Since this metal stopper has a structure not interfering with the stopper rubber at displacements in the circumferential direction or the forward or backward direction, the mountability of the apparatus is high as compared with that of the Prior Art 1, while the fixture does not have an ill influence upon the fixing bolts. However, since the metal stopper is bonded firmly with the elastic body at vulcanization of the elastic body, rubber burr is left on the metal stopper, so that the controlling of a stopper clearance, or distance between abutting surfaces, is difficult.
The metal stopper maybe formed separately from the elastic body and assembled thereto later so as to eliminate the problems due to the rubber burr. However, because the metal stopper is formed by merely bending a plate material so as to have a substantially sideway-fallen J-shaped cross section, a required rigidity of the metal stopper cannot be maintained against a large stress in the compression and drawing directions or in the lateral direction. When a flange is formed by bending the edges on circumferential-direction-wise end of the metal stopper in order to maintain the rigidity of the metal stopper, the flange necessarily hits the stopper rubber. Consequently, the Prior Art 2 has problems similar to those of the Prior Art 1.
In view of the above, second object of the present invention is solving at once the above-mentioned problems of the prior art, and for achieving altogether followingxe2x80x94the improvement of the mountability of the apparatus; the prevention of circumferential-direction-wise interference of the metal stopper with the stopper rubber; and an increase in the rigidity of the metal stopper.
First aspect of the present invention provides a vibration-isolating apparatus, having a structure basically identical with Prior Arts 1 and 2, capable to prevent a slip-off of the metal stopper in the drawing direction by improving the metal stopper, and thereby improve the durability and reliability of the apparatus.
According to the first aspect, the vibration-isolating apparatus includes a first fixture; a second fixture; a vibration-isolating base body interposed between these two fixtures and formed of an elastic material having rubber-like elasticity; a stopper rubber projecting outward so as to restrict a large displacement of the vibration-isolating base body; and a metal stopper surrounding this stopper rubber; and the metal stopper being formed by bending a metal plate or sheet. The metal stopper has contact surfaces respectively parallel to stopper surfaces of the stopper rubber, for restricting displacements in following directionxe2x80x94a compression direction in which the first and second fixtures are moved relatively toward each other; a drawing direction in which the first and second fixtures are moved away from each other; a radial direction perpendicular to the compression and drawing directions; and a circumferential direction. A drawing-side contact surface of the metal stopper, which is for restricting a displacement in the drawing direction, inclines in an angle range of 10xc2x0-50xc2x0 with respect to a plane perpendicular to the compression and drawing directions. An inner edge of the drawing-side contact surface projects inward from the radial-direction-wise contact surface by a distance which is not smaller than 10 mm, and which permits the inner edge not to contact the vibration-isolating basebody. Thus, a slip-off of the metal stopper can be prevented even when a large deformation occurs momentarily in the vibration-isolating base body.
The reason why the angle of inclination of the drawing-side contact surface and the distance by which the inner edges of the drawing-side contact surface projects are set in the mentioned ranges in this vibration apparatus is followingxe2x80x94these ranges constitute the necessary and satisfactory conditions for meeting requirements of manufacturing and designing the metal stopper with respect to strength and rigidity. For example, when the angle of inclination is smaller than 10xc2x0, difficulties occur in the manufacturing of the metal stopper, and, when the angle of inclination exceeds 50xc2x0, there is a fear that the metal stopper slips off when a momentary large displacement of the vibration-isolating base body occurs. When the distance by which the inner edge of the drawing-side contact surface is smaller than 10 mm, there is a fear that the metal stopper slips off when a momentary large displacement of the vibration-isolating base body occurs.
In order to prevent the metal stopper from being slipped off, it is demanded that the metal stopper has such rigidity and strength that does not cause the metal stopper to be elastically deformed even with respect to a momentary large deformation of the vibration-isolating base body. To meet this requirement, it is preferable to set the thickness of the metal stopper large, and secure the rigidity and strength thereof. Generally, the stopper rubber has following structurexe2x80x94a part of an outer circumferential edge of the second fixture is extended radially; an enclosing rubber portion encloses this extended portion; the stopper rubber comes into contact with the metal stopper when the vibration-isolating base body is greatly deformed. Accordingly, it is desirable to set the thickness of the metal stopper larger than that of the extended portion extended from the second fixture, which portion is enclosed in the stopper rubber.
In order to increase the rigidity and strength of the metal stopper, it is preferable that outwardly extending flanges are formed on edge portions of circumferential-direction-wise contact surfaces while an angle at which the flanges are bent set in the range of 45xc2x0-90xc2x0 so as to withstand a large stress.
This vibration-isolating apparatus maybe of various kinds as long as it has a stopper mechanism and preferably have high vibration isolating and damping performance.
Second aspect of the present invention is to achieve the second object of the invention mentioned earlier, by adopting the following structure for the metal stopper.
A vibration-isolating apparatus of this aspect of the invention, which has same basic construction as in the first aspect of the invention, comprises a first fixture on the upper side; a second fixture on the lower side; a vibration-isolating base body formed of an elastic member having rubber-like elasticity; a stopper rubber projecting outward from the portion of the vibration-isolating base body which portion is on the side of the lower side fixture; and a metal stopper opposed to the stopper rubber. The stopper rubber and the metal stopper serves for restricting displacements in-an axial direction in which the first and second fixtures are moved relatively toward and away from each other, and in a radial direction. The metal stopper further comprising a reinforcing flange for enhancing. rigidity of the metal stopper, being formed to be continuous radially by downwardly bending an edge of the metal stopper except for a region that is subject to interference of the stopper rubber at a time of large displacement of the metal stopper in a circumferential direction relative to the stopper rubber; and a rigid reinforcing rib projecting outward from a circumferential-direction-wise center portion of the metal stopper except for a region having the reinforcing flange, so that the rigid reinforcing rib and the reinforcing flange are formed to be continuous in the radial direction over whole radial dimension of the metal stopper in view from the circumferential direction.
Owing to such a structure, the metal stopper does not interfere with the stopper rubber when the vibration-isolating base body is displaced greatly in the circumferential direction, while the bending rigidity of the metal stopper is improved. Furthermore, since the reinforcing flanges extend downward, the circumferential dimension thereof does not increase, while the efficiencies or easiness for fixing and mounting the metal stopper is improved. Since the metal stopper is formed separately from the elastic body, the controlling of a distance between the metal stopper and the stopper rubber can be done easily, unlike a similar control operation in the prior art.
The reasons for providing the rigid reinforcing rib so as to project outward from a circumferential-direction-wise center portion of the metal stopper reside in that, when the. reinforcing rib is formed on a circumferential-direction-wise end portion, it substantially becomes an extension of the reinforcing flanges and interferes with the stopper rubber at a large displacement in the circumferential direction. When the reinforcing rib is projected inward, it also interferes with the stopper rubber.
Forming the reinforcing flanges and reinforcing rib continuously in the lateral direction mentioned above does not mean that both of these parts are in a physically continuous state but it means that the reinforcing flanges and reinforcing rib are joined together in the radial direction when the metal stopper is viewed in the circumferential direction. The reinforcing flanges may not be formed over the whole radial dimension of the metal stopper as long as the metal stopper can secure a predetermined level of bending rigidity. The reinforcing flanges may be formed to be starting from a radially outside intermediate portion thereof. Concretely speaking, the reinforcing flanges may be formed to be starting from a radial-direction-wise intermediate part of a flat portion that will be described later.
The metal stopper is opposed to the stopper rubber provided on the radially outer side of the elastic body that is bonded to upper and lower fixtures at a vulcanization process. The metal stopper is formed by press-working one single piece of pressed steel plate. The metal stopper has a flat plate portion contacting the upper fixture; an upper stopper portion extending from one radial-direction-facing edge of the flat plate portion; a radially-inward-facing stopper portion continuing from the upper stopper portion; and a lower stopper portion continuing from the radially-inward-facing stopper portion. Thus, stopper functions are displayed against displacements in axial and radial directions.
It is especially desirable for combining a construction of the lower stopper portion in the first aspect of the invention to this second aspect of the invention, in order for preventing a slip-off of the metal stopper when a large deformation of the vibration-isolating base body occurs in the drawing direction. Namely, the angle of inclination of. the lower stopper portion is set in the range of 10xc2x0-50xc2x0 with respect to a plane perpendicular to a vertical direction in which the two fixtures are moved relatively toward and away from each other. Further, an inner edge of the drawing-wise contact surface projects radially inward from the second contact surface by not less than 10 mm so as not to contact with the vibration-isolating base body.
It is preferable to place a pair of such vibration-isolating apparatuses on left and right portions of the interior of an engine room of an automobile, and fix the apparatuses to rightwardly and leftwardly inclined brackets associated with a vehicle body, by using fixing bolts projecting downward from the lower fixtures of these apparatuses. However, vibration-isolating apparatuses may be disposed in a various manner other than the above.
When these apparatuses are fixed to the rightwardly and leftwardly inclined brackets in the automobile, the fixing bolts of the upper and lower fixtures are inclined in accordance with the inclination of the brackets in the vehicle. Therefore, even when stress should be exerted on the apparatuses in the rightward or leftward direction, the bending stress exerted on the fixing bolts of the lower fixture also becomes small, so that the damage to the fixing bolts and to sealing between the lower fixtures and the fixing bolts decrease.
Because the vibration-isolating apparatuses in this aspect do not have a stopper mechanism for restricting a displacement in a circumferential direction that coincides to rightward or leftward direction of the vehicle, it is preferable to use another vibration-isolating apparatus having a stopper mechanism for restricting a displacement in forward or backward direction of the vehicle, on forward side or backward side of the engine room.
This vibration-isolating apparatus may be of various kinds as long as it has a stopper mechanism and preferably have high vibration isolating and damping performance.